Resource exhaustion in Symfony Ux

CVE-2026-49209

Symfony UX is a JavaScript ecosystem for Symfony. From 2.5.0 until 2.36.0 and 3.1.0, Symfony\UX\LiveComponent\Controller\BatchActionController::__invoke() iterates over the client-supplied actions array and issues a full HttpKernel sub-request for each entry; because the array size is never bounded, an authenticated client can submit a single _batch request containing thousands of actions and exhaust CPU, memory, and database connections on the application server. This issue is fixed in versions 2.36.0 and 3.1.0.

Published · last modified .

CVSS v3 metric

CVSS v3 base score 6.5 (Medium). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H.

EPSS exploit prediction

EPSS: 0.006 (45.9th percentile), scored .

Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 46th percentile — 45.9% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.

EPSS trend (30 days)EPSS over the last 30 days for CVE-2026-49209: held from 0.006 to 0.006.

EPSS over last 30 days · oldest: 0.006 · newest: 0.006 · change: 0.000

Affected products

  • Symfony Ux — versions >= 3.0.0, < 3.1.0, >= 2.5.0, < 2.36.0, 3.0.0

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-49209?
CVE-2026-49209 is a medium-severity vulnerability in Symfony Ux, classified under Allocation of Resources Without Limits or Throttling. CVSS score: 6.5/10. Published 2026-07-17.
How severe is CVE-2026-49209?
Medium severity. CVSS v3 base score is 6.5 out of 10.